Cannot call out site through Ipad Air 2

[quoctrang]

Dear Friends ,
I've installed Alcatel IP softphone version 11.0.4.2 on my IPad Air 2 .
My PABX OXE has license for IP softpohne user .
I can make local throuhg my Ipad , but I cannot make outgoing call .When I press"9" on my Ipad , there's a tone , but I continue to press number outside , it's silent , no tone

The configuration on my Ipad are as below :
- Professional trunkSeise 9
- Internation 00
- National 0
- Contry code Vietnam 84
Park call 402

Could you please help us so that I can make a uotside call throuhg my Ipad ?

thanks and best regards